![]() ![]() A normal ADI confirms that the transverse ligament is intact. One should be cognizant of these differences to avoid confusing them with pathologic conditions.Ītlantodens Interval (ADI): The ADI is defined as the distance between the anterior aspect of the dens and the posterior aspect of the anterior ring of the atlas. There are several normal anatomic differences that may be encountered on the pediatric cervical spine. The secondary ossification centers at the superior and inferior aspects of the cervical vertebral bodies, the endplates, can remain unfused until early adulthood. In addition, there are secondary ossification centers at the tips of the transverse processes and spinous processes that may persist until early in the third decade of life, simulating a fracture. The neural arches fuse posteriorly by age 2-3 years and the body fuses with the neural arches between 3-6 years of age. There are three primary ossification sites for each vertebral segment: the vertebral body, which develops from a single ossification center, and two neural arches. The vertebrae of C3 through C7 can be discussed as a group because they demonstrate the same developmental pattern. Figure 1: The space between the lateral masses relative to the dens can be < 6 mm, but the lateral masses of C1 can still remain aligned with the lateral masses of C2 in the pediatric spine. The neural arches fuse posteriorly by 2-3 years of age and with the body of the odontoid process between 3-6 years of age. This fusion line can be seen until age 11 years and should not be confused with a fracture. A secondary ossification center appears at the apex of the odontoid process between 3-6 years of age. The odontoid process forms in utero from two separate ossification centers that fuse in the midline by the seventh fetal month. There are four ossification centers at birth: one for each neural arch, one for the body and one for the odontoid process. The neural arches fuse posteriorly by 3 years of age.Ĭ2 is the most complex developmental and ossification process of all the vertebrae. The anterior arch fuses with the neural arches by 7 years of age nonfusion should not to be mistaken as a fracture. The neural arches appear at the seventh fetal week. The anterior arch is ossified only in 20 percent of children at birth with the other 80 percent it becomes visible as an ossification center by 1 year of age. C1 is formed by three primary ossification sites, the anterior arch and the two neural arches, which fuse to form the posterior arch. The first two cervical vertebrae are unique. Therefore, familiarity with the normal anatomy will help avoid misinterpretations. The interpretation of pediatric cervical spine X-rays can be challenging, even for the most experienced, because of the wide range of normal anatomic variants and changes that occur with the maturation / ossification process. Depending on the age of the child, there may be incomplete ossification of the odontoid process add to this the relatively large head and weak neck muscles, and the pediatric spine is predisposed to increased instability compared to the adult spine. The fulcrum of motion in the pediatric cervical spine is at the C2-3 level, whereas in the adult it is at the C5-6 level.Ī child's spine is hypermobile compared to an adult's because of the relative ligamentous laxity, shallow and angled facet joints, underdeveloped spinous processes, and physiologic anterior wedging of vertebral bodies. Cervical spine injuries in children usually occur in the upper cervical region from the occiput to C3. The main fact one should remember is that the pediatric cervical spine not the same as the adult biomechanically. This is a brief review of the main radiographic features that one should be aware of in order to avoid confusing normal differences with pathologic findings. There are several normal anatomical differences between the adult and the pediatric cervical spine. ![]()
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